Suction control device for multiple cylinder internal combustion engine

ABSTRACT

A suction control device for a multiple cylinder internal combustion engine comprising a shell body presenting a suction path communication to each cylinder in a multiple cylinder internal combustion engine, a rotary shaft (21a) penetrating and born by the shell body, a butterfly valve (21) supported by the rotary shaft and provided in each of the suction paths so that it can freely open or close the suction path, and a restricting means for restricting movement of the rotary shaft in the axial direction; wherein the rotary shaft and the butterfly valve are monolithically formed with a resin material, the shell body is made from a resin material, and the restricting means comprises an expanding piece (21b) monolithically formed on the rotary shaft and having a width in the radial direction thereof, a contact wall (24) formed on the shell body and slidably contacting and supporting the expanding piece, and a resilient energizing member (33) for energizing the expanding piece to contact it to the contact wall. With this feature, the weight reduction of the device can be achieved and also the rotary shaft can bee accurately and precisely supported in the thrust direction and can be prevented from becoming loose.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a suction control device for a multiplecylinder internal combustion engine incorporated in a vehicle or thelike, and more particularly to a suction control device for a multiplecylinder internal combustion engine with specific features in thebutterfly valve opening and closing a suction path and the bearing ofthe rotary shaft therefor, and the tightening construction betweenmembers thereof.

2. Background Technology

Conventionally, so-called a variable suction system, in which a lengthof a suction pipe and a path capacity are switched in two stagesaccording to such factors as a rotational speed of an engine or a loador the like to give an inertia supercharge effect or a resonancesupercharge effect to intake air for the purpose to improve output fromthe engine, has been employed as a suction system for an engine.

FIG. 1 shows a cross sectional view of the suction control devicewherein the variable suction system described above is employed for asix-cylinder engine. In this figure, a cross section of one suction pathcorresponding to one-cylinder of engine is shown, but actually thesuction paths corresponding to six cylinders thereof are formedmonolithically in parallel in a direction vertical to the sheet carryingthis figure.

In the suction control device described above, the intake air introducedfrom a side end of the body into a surge tank 1 via a throttle valve(not shown herein) is introduced into an engine cylinder, passes througha roundabout suction path 3 as shown by the arrow A when a switch valve2, which is a butterfly valve, is closed by operation of an actuator(not shown) if the speed is in a range of low or medium level (a stateshown by a solid line), while, if in a range of high speed, the switchvalve 2 is in the open state (a state shown by a two-dot chair line),and the intake air is directly introduced into the engine cylinderwithout passing through a roundabout suction path 3 as shown by thearrow B.

Namely, by opening and closing the switch valve 2, pressure invertedwave generated through a long suction pipe is synchronized in a low andmedium range of speed and that generated through a short suction pipe issynchronized in a high range of speed for thereby improving the chargingefficiency in the entire range of speed, thus improvement of torque in alow/medium speed range and that of maximum output power being achievedconcurrently.

Also, in the suction control device employing the variable suctionsystem as described above, a body section thereof presenting a suctionpath as well as a surge tank or others is molded by using aluminummaterial, and the changing valve 2 as well as the rotary shaft 2atherefor are molded by using steel or the like.

And because of the restrictions in the molding technology as describedabove, a suction control device is separated into three areas, namely abranch portion (I) forming only a suction path, a valve body portion(II) presenting a changing valve 2 therein which is a multiple butterflyvalve and also forming a suction path, and a cover portion (III) forminga surge tank 1 and presenting a port shell 4 therein constituting aportion of the roundabout suction path 3, and each of the three portionsis molded discretely, and then each of the mounting flange surfaces ismonolithically butt-jointed to each other by using a connecting means(not shown) such as bolts and nuts or the like.

Furthermore, as for the multiple butterfly valve, as shown in FIG. 2, aconcave notch is formed in a portion corresponding to each suction pathof a line of the rotary shaft 2a, a valve 2 is fixed by using atightening means such as a bolt 2b in this area, and a driving meanscomprising, for instance, an arm 2 and an actuator 5 is connected in oneend of the rotary shaft 2a with the above-described valve 2 fixedthereto, so that all valves can monolithically be rotated.

Also, as for an assembly method and a supporting method for thismultiple butterfly valve, as shown in FIG. 3, the rotary shaft bearinghole 6 is formed by drilling or the like so that the rotary shaftbearing hole is orthogonal to each of the suction path from the outerside of the valve body portion (II), then the rotary shaft 2a isinserted from the open outer side of the bearing hole 6, and after thatthe valve 2 is fixed to the rotary shaft with a small screw 2b in eachsuction path.

In this case, the rotary shaft 2a is supported in the radial directionby the internal wall of the bearing hole 6 itself. On the other hand,the rotary shaft 2a is supported in the thrust direction, as shown inFIG. 3, by providing a spring 7 energizing the rotary shaft 2a in thedirection indicated by the arrow and associated with one end of therotary shaft 2a, and also bringing the peripheral side 2d of the valve 2into contact with the internal wall of the suction path 8.

In the supporting construction in the thrust direction described above,a spring 7 having a spring constant within a specified range is requiredto be selected so that scuffings do not occur in the engaged slidingsection between the peripheral side 2d of the valve 2 and the internalwall of the suction path, and also a selectable width thereof islimited. Also, the valve and the internal wall of suction path aresometimes deformed, which may cause the rotary shaft not to rotatesmoothly because of a partial abrasion caused by increase of localbearing stress under the effects of atmospheric temperature ordisplacement of the alignment.

Also, in the bearing construction as described above, if there occurs achange of a clearance in the bearing section due to difference incoefficients of thermal expansion in a case where the rotary shaft 2aand the valve body 1 are formed with different types of materialsrespectively, change of a clearance in the bearing section due todeterioration over time such as a abrasion, or dispersion of clearancein the bearing section due to dispersion in a manufactured size aregenerated, the change of a clearance as described above can not becompensated, and for this reason, the rotary shaft 2a may rattle and tapin the bearing hole, and the valve body may contact the internal wall ofthe suction path. And more particularly in a case of a multiplebutterfly valve, the bearing stress of the bearing section becomespartially larger, so that the bearing section has a tendency to becomeloose due to abrasion or plastic deformation, because a torque deliverymeans such as an actuator 3 is provided in one end of the multiplebutterfly valve although it has a long size.

As a structure for connection between a surge tank and a throttle bodyin the conventional technology, the structure as shown in FIG. 4 to FIG.6 has been known.

Herein, FIG. 4 shows a plan view of a suction device for engine, and inthis case the suction control device is separated into three areas,namely a branch portion (I) forming only a suction path, a valve bodyportion (II) presenting a switch valve which is a multiple butterflyvalve and forming a suction path, and a covering portion (III) forming asurge tank and presenting a port shell therein constituting a portion ofthe roundabout suction path, and each of the portions is discretelymolded by using aluminum material, then the mounting flange surfaces aremonolithically butt-jointed to each other by using a connecting means(not shown) such as bolts or others.

Also, a flange section 100a having an opening is provided on the portionof the peripheral wall of the valve body (II) forming the surge tank andthe covering portion (III), and the throttle body 200 presenting thethrottle valve therein for adjusting output of engine is fixed andtightened with bolts 300 by contacting the flange section 200a to theflange section 100a. It should be noted that the throttle body 200described above is also formed with aluminum material, and the rotarydrum 200d, to which wire or the like is hooked, is fixed to one end ofthe rotary shaft 200c supporting the throttle valve (not shown) providedin the suction path, and the throttle valve can be opened or closed byrotating the rotary drum 200d.

Herein, detailed description is made for structure for connecting thethrottle body 200 to the flange section 100a of the body of suctiondevice 100, and as shown in FIG. 5 illustrating a cross section of thethrottle body taken along the line A--A in FIG. 4, a screw hole 100s isformed in a flange section 100a of the body of suction device (totally 4pieces of screws each at four corners), and on the other hand athrough-hole 200h is formed in the flange section 200a of the throttlebody (also 4 pieces totally). And a bolt 300 with a flat washer or aspring washer 500 assembled thereto is screwed into the screw hole 100sby inserting through the through-hole 200h described above in a statewhere both end surfaces of the both flanges are engaged and connected toeach other through the seal member 400, then the both end surfaces arefirmly connected and tightened to each other.

Also, another structure for connection is shown in FIG. 6. Herein, thethrough-hole 100h is formed in place of a screw hole in the flangesection 100a of the body of suction device and the both flanges areconnected to each other with a bolt 300 and nut 700 through a flatwasher 500 and spring washer 600.

By the way, as one of the policies for development of more advanced, thepossibilities of development of low fuel-consumption vehicles byreducing weight thereof, and also development of low-cost vehicles bychanging materials or simplifying production process thereof have beeninvestigated.

For this reason, in the suction device as described above,conventionally molded from metal materials such as aluminum material orthe like, the possibility of manufacturing the products with resin hasbeen investigated as part of the efforts for development of moreadvanced vehicles.

However, even if the components constituting the conventional type ofsuction control device are formed with resin, there arise such newproblems as that mechanical strength of resin materials is weak and adegree of assembling precision is lower because of effects by lowerheat-transfer properties or lower molding precision in each componentsthereof as compared to those of metal materials.

Also, even if all components constituting the conventional type ofsuction device is formed with resin, when the conventional type ofconnecting structure is employed and the throttle body is fixed thereby,there arise such new problems as that mechanical strength of the resinflange section is weak, the connecting section is loosened due to thesettling of the flange section caused by heat creep or the like, formingof screw holes is difficult, and post-processing thereof is alsodifficult, so that it is found difficult to insure the connectingstrength and reliability of the components at the same level as those inthe conventional technology.

SUMMARY OF THE INVENTION

The present invention was made in the light of the circumstances asdescribed above, and it is a first object of the present invention toprovide a suction control device for a multiple cylinder internalcombustion engine in which functions the device should have by naturecan accurately and precisely be operated and also which enables weightreduction in products.

A second object of the present invention is to provide a suction controldevice for a multiple cylinder internal combustion engine in whichrequired function can precisely be operated especially by precisepositioning to the device body of a multiple butterfly valve and alsowhich enables weight reduction in products.

A third object of the present invention is to provide a suction controldevice for a multiple cylinder internal combustion engine in which abearing section for a rotary shaft can be prevented from becoming loosewithout being affected by materials for molding, peripheral temperature,or deterioration of materials over time and the bearing section canachieve the original functions at a high precision without fail, andalso which enables weight reduction in products.

A fourth object of the present invention is to provide a suction controldevice for a multiple cylinder internal combustion engine having astructure for connection between of a surge tank and a throttle bodywhich enables firmer connection between the two components bymaintaining the connecting strength in the initial stage and an easierwork for connection even if a connecting flange section is formed with aresin material of which mechanical strength is weak.

The suction control device for a multiple cylinder internal combustionengine according to the present invention comprises a shell bodypresenting a suction path communicated to each cylinder in amulti-cylinder internal combustion engine, a rotary shaft penetratingand born by the shell body, and a butterfly valve supported by therotary shaft and provided in each of the suction paths so that it canfreely open or close the suction path, and is characterized in that thebutterfly valve and the rotary shaft are made from a monolithicallymolded resin material, and the shell body is formed with a resinmaterial.

Also the suction control device for a multiple cylinder internalcombustion engine comprises a shell body presenting a suction pathcommunicated to each cylinder in a multiple cylinder internal combustionengine, a rotary shaft penetrating through and born by the shell body,and a butterfly valve supported by the rotary shaft and provided in eachof the suction paths so that it can freely open or close the suctionpath, and is characterized in that a peculiar form hole having a crosssection other than a circle is formed in the butterfly valve, the rotaryshaft has the same cross section in a direction perpendicular to theaxial line as that of the peculiar form hole, and the rotary shaft isinserted into and engaged with the peculiar form hole to penetratethrough and support each butterfly valve provided in the suction path.

With the suction control device for a multiple cylinder internalcombustion engine according to the present invention, the butterflyvalve and the rotary shaft are monolithically formed with a resinmaterial, so that an internal stress due to heat does not occur becausecoefficients of the thermal expansion of the valve and the rotary shaftare identical even when the engine is affected by heat from outside, andalso orientation of resin fiber becomes identical in the engagementsection between the valve and the rotary shaft because they aremonolithically made, and for this reason the mechanical strength can beinsured.

In addition, with the penetrated butterfly valve, the valve can beengaged with the rotary shaft without using the conventional type ofconnecting means, so that functions of the butterfly valve cansufficiently be achieved.

Also, the suction control device for a multiple cylinder internalcombustion engine according to the present invention comprises a shellbody presenting a suction path communicated to each cylinder in amultiple cylinder internal combustion engine, a rotary shaft penetratingthrough and born by the shell body, a butterfly valve supported by therotary shaft and provided in each of the suction paths so that it canfreely open or close the suction path, and a restricting means forrestricting movement of the rotary shaft in the axial direction, and ischaracterized in that the butterfly valve and the rotary shaft aremonolithically formed with a resin material, the shell body is made froma resin material, and the restricting means comprises an expanding piecemonolithically formed on the rotary shaft and having a width in theradial direction thereof, a contact wall formed on the shell body andslidably contacting and supporting the expanding piece, and a resilientenergizing member for energizing the expanding piece to contact it tothe contact wall.

Also, the suction control device for a multiple cylinder internalcombustion engine according to the present invention comprises a shellbody presenting a suction path communicated to each cylinder in amultiple cylinder internal combustion engine, a rotary shaft penetratingthrough and born by the shell body, a butterfly valve supported by therotary shaft and provided in each of the suction paths so that it canfreely open or close the suction path, a driving means for driving therotary shaft, and a restricting means for restricting movement of therotary shaft in the axial direction, and is characterized in that thedriving means has a torque delivery rotary member engaging and connectedto one end section of the rotary shaft, the restricting means has acontact piece contacting an end face of the torque delivery rotarymember from outside of the rotary shaft in the axial direction thereof,and the resilient energizing member for contacting the other end of therotary shaft from outside thereof in the axial direction and energizingrotary shaft toward the contact piece.

With the suction control device according to the present invention, asthe expanding piece formed monolithically on the rotary shaft iscontacted to the contact wall formed on the shell body, the movement ofthe rotary shaft in the axial direction is restricted and energized bythe resilient energizing member, it is possible to prevent the rotaryshaft from becoming loose. With this feature, each butterfly valvesupported by the rotary shaft can accurately execute opening/closingoperation at the specified position of the suction path.

Also, the movement of the rotary shaft as described above can also berestricted by the contact piece contacting an outer end face of thetorque delivery rotary member delivering torque to the rotary shaft, andby resilient energizing member energizing the rotary shaft toward thecontact piece at the other end of the rotary shaft, so thatopening/closing operation of the butterfly valve can accurately beexecuted without generating rattling therein.

Also, the suction control device for a multiple cylinder internalcombustion engine according to the present invention comprises a shellbody presenting a suction path communicated to each cylinder in amultiple cylinder internal combustion engine, a rotary shaft penetratingthrough and born by the shell body, a bearing supporting the rotaryshaft in the radial direction, a butterfly valve supported by the rotaryshaft and provided in each of the suction paths so that it can freelyopen or close the suction path, and is characterized in that the bearinghas an engagement section which is engaged in a hole for engagementprovided on an external wall of the shell body and a bearing sectionengaged in the axial direction of the rotary shaft and supporting therotary shaft in the radial direction, and a resilient contact pieceenergizing the rotary shaft in the radial direction is monolithicallyformed in the bearing section.

With the suction control device according to the present invention, forinstance, the multiple butterfly valve in the suction device is providedat a specified position of the suction path formed in the valve bodywhich is the shell body, then positioning is made by engaging theengagement section of the bearing in the hole for engagement provided onthe valve body and the bearing section is engaged in the rotary shaftwhen the rotary shaft is supported to the valve body described above. Inthis state, the resilient contact piece formed monolithically on thebearing section all the time energizes the rotary shaft in the radialdirection. Even if the sliding section is worn out or a clearancethereto changes, the resilient contact piece always follows andcompensates the change, so that the rotary shaft in the bearing hole canbe prevented from being loosened therein.

Furthermore, in the suction control device for a multiple cylinderinternal combustion engine according to the present invention, a flangesection of the throttle body for adjusting output from the engine iscontacted to a surge tank flange section forming a portion of a suctionsystem for the multiple cylinder internal combustion engine and the twoflange sections are connected to each other by the connecting means, andthe suction control device according to the present invention ischaracterized in that the surge tank flange section is made from a resinmaterial and at the same time the connecting means comprises a boltpenetrating through a through-hole provided between the surge tankflange section and the flange section of the throttle body and a nutscrewed into the bolt, furthermore the nut comprises a cylindrical screwsection having a female screw groove in the internal wall and arectangular flange one end having a width in the radial direction in oneend of the cylindrical screw section in the axial direction thereof, andthe surge tank flange section has a U-shaped notched engagement grooveopening toward outside in the direction of a flange surface of theflange section and also has a projection for contacting the cylindricalscrew section to an internal periphery of the notched engagement groovein a state where the cylindrical screw section is inserted into andengaged in the notched engagement groove and pressing the cylindricalscrew section to the bottom of the notched engagement groove.

In the suction control device according to the present invention, thenut is one with flange comprising a cylindrical screw section and aflange section, and the engagement section at which the nut with flangeis connected to the flange section is a U-shaped notched engagementgroove opening toward outside in the direction of a flange surface ofthe flange section, and furthermore the projection for making partiallynarrow the groove width of the engagement groove is formed in theinternal wall of the groove, so that when the cylindrical screw sectionof the nut with flange is inserted into and engaged in the notchedengagement groove described above, the projection is deformed in a rangeof resilience to enable its insertion, and the external periphery of thecyrindrical screw section is held and fixed thereby according to theelastic recovery of the projection after the insertion.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel,are set forth with particularity in the appended claims. The invention,together with further objects and advantages, may best be understood byreference to the following description taken in conjunction with theaccompanying drawings, in the several Figures of which like referencenumerals identify like elements, and in which:

FIG. 1 shows a cross-sectional view of the conventional type of suctioncontrol device;

FIG. 2 shows a schematic perspective view illustrating a multiplebutterfly valve used in the conventional type of suction control device;

FIG. 3 shows a cross-sectional view illustrating a supporting structureof the multiple butterfly valve in the conventional technology,

FIG. 4 shows a plan view illustrating the tightening state of the surgetank in a suction system with the throttle body in the conventionaltechnology; and

FIG. 5 shows a cross-sectional view illustrating the throttle body takenalong the line A--A in FIG. 4.

FIG. 6 shows prior art similar to FIG. 5.

FIG. 7 shows a plan view of the suction control device according toembodiments of the present invention;

FIG. 8 shows a side view illustrating appearance of the suction controldevice from the point of the arrow R shown in FIG. 7;

FIG. 9 shows a side view illustrating an appearance of the suctioncontrol device from the point of the arrow L shown in FIG. 7; and

FIG. 10 shows a cross-sectional view illustrating the suction controldevice taken along the line C--C in FIG. 7.

FIG. 11 shows a plan view illustrating a monolithic type of the multiplebutterfly valve of the suction control device according to the presentinvention;

FIG. 12 shows a side view illustrating the same as described above froma point of the arrow S shown in FIG. 11; and

FIG. 13 shows a cross-sectional view illustrating the butterfly valvetaken along the line D--D in FIG. 11.

FIG. 14 is a partial perspective view illustrating appearance of thepenetrated butterfly valve of the suction control device according tothe embodiment of the present invention.

FIG. 15 to FIG. 18 are views each illustrating the bearing in thesuction control device according to an embodiment of the presentinvention; FIG. 15 is a side view showing a state where the rotary shaftis supported; FIG. 16 is a side view showing the state where a pair ofengaging pieces are disengaged from each other, FIG. 17 is a plan viewshowing the state in FIG. 16; and FIG. 18 is a cross-sectional viewshowing the same state as that in FIG. 16 taken along the line F--F inFIG. 17.

FIG. 19 is a cross-sectional view illustrating a bearing engagementsection formed in the valve body (II), and

FIG. 20 is a view showing a manufacturing process for the intermediatebearing engaged in and fixed to the engagement section described above.

FIG. 21 is a cross-sectional view illustrating a state where theintermediate bearing is engaged in and fixed to the bearing engagementsection of the valve body (II) by means of heat caulking welding.

FIG. 22 to FIG. 25 are a side view, a plan view, and a cross-sectionalview each illustrating appearance of the bearing in the suction controldevice according to another embodiment of the present invention.

FIG. 26 is a side view illustrating appearance of the bearing in thesuction control device according to another embodiment of the presentinvention, and

FIG. 27 is a view illustrating a manufacturing process for the bearingdescribed above engaged in and fixed to the bearing engagement sectiondescribed above.

FIG. 28 is a front view illustrating an end bearing supporting the endsection of the monolithic type of multiple butterfly valve in thesuction control device according to the present invention, and

FIG. 29 is a cross-sectional view illustrating the end bearing takenalong the line H--H in FIG. 28.

FIG. 30 is a cross-sectional view showing the state where the endbearing shown in FIG. 28 and FIG. 29 is mounted from outside of thevalve body (II) to support the rotary shaft.

FIG. 31 is a cross-sectional view illustrating the device taken alongthe line B--B in FIG. 7, and illustrating an embodiment of the thrustbearing structure with specific features in the present invention.

FIG. 32 shows another embodiment of the thrust bearing construction withspecific features in the present invention.

FIG. 33 is a perspective view illustrating a connected structure betweenthe worm wheel and the rotary shaft according to the embodiment shown inFIG. 32.

FIG. 34 is a plan view illustrating the suction device and throttle bodyemploying the tightening structure according to the present inventionand

FIG. 35 is an external side view illustrating the suction device fromthe point of the arrow R shown in FIG. 34.

FIG. 36 and FIG. 37 each show an embodiment of the tightening structureaccording to the present invention, and FIG. 36 is a perspective viewillustrating appearance of an flange section made from resin and a nutwith flange, and FIG. 37 is a view showing the state where the nut withflange is engaged in the notched engagement groove.

FIG. 38 shows an embodiment of the connecting structure according to thepresent invention, and is a cross-sectional view illustrating thereabovetaken along the line J--J in FIG. 34.

FIG. 39 is a cross-sectional view illustrating another connectingstructure using a counter-sunk spring as a resilient member.

BEST MODE FOR CARRYING OUT THE PRESENT INVENTION

Description is made hereinafter for a first embodiment of the suctioncontrol device for a multiple cylinder internal combustion engineaccording to the present invention with reference to the relateddrawings.

FIG. 7 shows a plan view illustrating appearance of the suction controldevice, and as shown in the figure, the suction control device comprisesa combination of resin injection molding components forming three areasof I, II, and III respectively. Namely, the portion of blanch (I)connected to the head air inlet port of the engine, the portion of valvebody (II) as a shell body presenting therein a multiple butterfly valvewhich is a switch valve for intake air, and the covering portion (III)forming the surge tank and the roundabout suction path each are formedby the method of injection molding discretely, and then the componentsare monolithically connected with each other through each flange surfacefor engagement by means of vibration welding or the like.

FIG. 8 shows a side view illustrating appearance of the suction controldevice from the point of the arrow R shown in FIG. 7, and as shown inthe figure, and the flange section 10 for mounting thereto the throttlebody adjusting output from the engine is formed herein.

FIG. 9 shows a side view illustrating the suction control device fromthe point of the arrow L shown in FIG. 7, and, as shown in the figure,the actuator 30 presenting therein a gear system driving the multiplebutterfly valve provided therein is mounted to the peripheral sidedescribed above.

It should be noted that the reference numeral 20 shown in FIG. 7 andFIG. B indicates appearance of the edge bearing supporting one edge ofthe rotary shaft for the valve in the radial direction, and the rotaryshaft of the multiple butterfly valve is provided at this position.

FIG. 10 shows a cross-sectional view illustrating the suction controldevice taken along the line C--C in FIG. 7. As shown in this figure,inside the portion of valve body (II), a monolithic type of the multiplebutterfly valve in which the butterfly valve 21 and the rotary shaft 21aare monolithically formed with a resin material is provided in thesuction path supported by the intermediate bearing 22 so that it canfreely rotate. Also, inside the portion of cover (III), the port shell40 for forming the roundabout suction path is provided and fixed bycontacting the internal wall of the portion of cover (III).

Herein, detailed description is made further for the monolithic type ofmultiple butterfly valve and the bearing portion therefor. As shown inFIG. 11, six pieces of butterfly valves 21 corresponding to the intakeair inlet port of the six-cylindrical engine are monolithically formedtogether with the rotary shaft 21a supporting the butterfly valve sothat it can freely rotate by using a resin material or the likeaccording to the method of injection molding.

Also, by forming monolithically a butterfly valve 21 and a rotary shaft21a as described above, a work for fixing them with screws as requiredin the conventional technology is not required any more, and inaddition, a distance between butterfly valves can precisely be formed ifpreviously taking into consideration contraction and deformation of themolding resin used for molding. Also, use of resin also enables weightreduction thereof, and for this reason, bearing stress in each of thesupporting section of bearing 20 and 22 can be reduced.

Also, as shown in FIG. 12, by smoothly forming a connection area betweenthe rotary shaft 21a connecting butterfly valves 21 to each other andeach butterfly valve 21 with a curved surface R therebetween, resin cansmoothly be filled in a mold die, and also concentration of stress inthe connection area described above can be mitigated.

Furthermore, as shown in the cross-sectional view taken along the lineD--D in FIG. 13, in the connection area of the butterfly valve 21 withthe rotary shaft 21a, the thick (padding) section E is provided torealize a streamlined form. The invention is not limited to theparticular details of the apparatus depicted and other modifications andapplications are contemplated. Certain other changes may be made in theabove described apparatus without departing from the true spirit andscope of the invention herein involved. It is intended, therefore, thatthe subject matter in the above depiction shall be interpreted asillustrative and not in a limiting sense. With this feature, flexuralrigidity of the butterfly valve in the rotating direction and adeflecting direction of the rotary shaft is improved, and flowresistance of an intake air can be reduced and inertia supercharge orresonant supercharge can more efficiently be acted in a state where thebutterfly valve is provided in the suction path.

The multiple butterfly valve described above is such that the butterflyvalve and the rotary shaft are monolithically formed, but even if abutterfly valve and a rotary shaft are formed separately like in theconventional technology, as shown in FIG. 14, if the hole for engagementof the butterfly valve is formed with a peculiar form 21b other than acircle and a rotary shaft 21c having a cross section engaged in thepeculiar form hole 21b is formed, the butterfly valve and the rotaryshaft become monolithic when engaged to each other, and for this reason,a specified connecting means such as a screw is not required. Namely itis a preferable structure from the point of reduction in a number ofcomponents thereof.

Next description is made for a bearing rotatably supporting the rotaryshaft of the monolithic type of multiple butterfly valve.

Like in the conventional technology (refer to FIG. 2), in a type inwhich a rotary shaft 2a and a butterfly valve 2 are formed separately,and only the rotary shaft 2a is inserted from the external side to thebearing hole 6 provided in the valve body (II), then the butterfly valve2 is mounted, the bearing hole 6 itself formed in the main body of thevalve body (II) may be sufficient as a bearing supporting theintermediate section of the rotary shaft, but on the other hand, in theconfiguration like the present embodiment in which a butterfly valve anda rotary shaft are monolithically formed, the rotary shaft can not beinserted to the bearing hole from the external side of the valve body.

Therefore, in the present invention, as shown in FIG. 10, FIG. 15 toFIG. 18, and FIG. 19 to FIG. 20, the intermediate bearing 22 formed witha resin material is employed. The intermediate bearing 22 describedabove comprises a pair of engaging pieces 22a as shown in FIG. 15 toFIG. 18. Herein, FIG. 15 shows a side view showing the state where therotary shaft is supported; FIG. 16 shows a side view showing the statewhere the pair of engaging pieces are disengaged; FIG. 17 shows a planview of FIG. 16; and FIG. 18 shows a cross-sectional view of the bearingtaken along the line F--F in FIG. 17. As shown in these figures, a pairof engaging pieces 22a are connected rotatively to the base section ofbearing 22k each via the thin section 22d respectively. The presence ofthe thin section 22d described above generates an effect as a joint,which makes it easy to engage and disengage a pair of engaging pieces22a. Also, a pair of resilient contacting pieces 22c are monolithicallyformed in the bearing section supporting the rotary shaft 21a so that itpresents a cantilever form as well as a portion of an arch. The pair ofresilient contacting pieces 22c always energize the rotary shaft in theradial direction in the state where the rotary shaft 21a is supported atthe bearing section, and for this reason the rotary shaft in the bearinghole is prevented from becoming loose. Also, with these resilientcontacting pieces 22c, even if a clearance in the initial stage changesbecause of deformation caused by expansion or shrinkage each of thebearing and rotary shaft, the contacting pieces can contact and supporteach other by following the change, so that the bearing can keep onworking accurately and precisely without being affected by such factorssuch as atmospheric temperature.

Herein, description is made for a sequence of assembling the monolithictype of multiple butterfly valve by using the intermediate bearing 22described above. At first, the rotary shaft supporting sections at thefive intermediate positions shown in FIG. 11 are located on the bearingsupport base 22k as shown in FIG. 16, and then a pair of engaging pieces22 are engaged as shown in FIG. 15 and locked with a hooking claw 22b.The 5 pieces of intermediate bearings 22 in the state as described aboveare engaged in and fixed to a bearing engagement section 22f formed inthe valve body (II). At the same time, the groove 22f and thearch-formed projection section 22g (refer to FIG. 18) formed in theintermediate bearing 22 each are engaged in the long size projectionsection 23b and the arch-formed groove 23a formed in the bearingengagement section 23, so that the intermediate bearing 22 canaccurately be positioned.

Also, like the engaging operation described above, a set pin 24 formedin the bearing engagement section is inserted into the engagement hole22e of the intermediate bearing 22, then an edge of the set pin 24 isdeformed by adding thereto heat or vibration, namely an effect as arivet is given thereto by means of heat caulking welding, so that theintermediate bearing 22 can accurately be fixed.

It should be noted that, when a fixing means with a set pin 24 isemployed, as shown in FIG. 21, a chamfer 22 is provided in the uppersection of the hole 22e, so that stress concentrated to the weldingsection after subjected to caulking welding by heat deformation can beloosened, and holding power by the set pin in the axial direction andthe vertical direction can efficiently be achieved.

As for another embodiment of the intermediate bearing 22, as shown inFIG. 22 to FIG. 25, the thin section 22d is provided in the edge ofbearing area, and a pair of engaging pieces 22a can easily be engagedand disengaged, or, as shown in FIG. 26 and FIG. 27, the bearing sectioncan have two components such as a half bearing 22i and a bearing cap 22hby being divided into half.

Next description is made for an end bearing formed with a resin materialindicated by the reference numeral 20 in FIG. 8. The end bearing 20supporting one edge of the rotary shaft of the monolithic type ofmultiple butterfly valve comprises, as shown in FIG. 28 and FIG. 29, abearing section 20b supporting the rotary shaft 21a in the radialdirection, a spigot joint section 20a for positioning by engaging thebasic body of bearing 20 in the engagement hole provided in the valvebody, and a hook section 20d connected to the valve body (II), andfurthermore, a resilient contacting piece 20c always energizing andsupporting the rotary shaft 21a in the radial direction ismonolithically formed in a cantilever form in the bearing section 20.

The resilient contacting piece 20c described above is provided, so thatthe rotary shaft can be prevented from becoming loose in the bearinghole. In addition to the effect of preventing rattling, the role as abearing function can accurately be achieved because it can follow achange in atmospheric temperature or the like.

Also, as a sequence of assembling the end bearing 20, the monolithictype of multiple butterfly valve is supported by intermediate bearings22 and located in the area of bearing engagement section 23 in the valvebody (II), and then, as shown in FIG. 30, it is mounted by being engagedin and fixed from outside to the end bearing-hole for engagement openedon the peripheral side of the valve body (II). At this time, the basicbody of bearing 20 is precisely positioned by means of engagementbetween the spigot joint 20a and the hole for engagement 25, and thehooking section 20d is engaged in the mounting flange 26 provided in thevalve body (II), so that the disengagement is prevented, which makesengagement between the engagement more secured.

The monolithic type of multiple butterfly valve and the bearing thereforwhich are specific features in the suction control device according tothe present invention described above are all formed by using a resinmaterial, and it is an invention completed in the processing for formingthem with resin, however, the present invention is not limited to a caseof using a resin material, and it can also be applied to a case whereother materials may be used for it.

As described above, with the suction control device for a multiplecylinder internal combustion engine of the present invention, weightreduction thereof can be achieved and mechanical strength thereof can beinsured by forming it with resin or because of such effects aselimination of components for connection due to monolithic formation ofa butterfly valve and a rotary shaft.

Also, with weight reduction of the butterfly valve itself, a supportingload on the bearing section becomes smaller and a degree of wearing ofmembers in the sliding interface can be reduced.

Furthermore, with a bearing which is another specific feature of thepresent invention, even if a butterfly valve and a rotary shaft formedmonolithically as described above is supported by the bearing, theassembly thereof becomes possible, and it is possible to prevent therotary shaft becoming loose in the radial direction.

Also, even if the bearing described above is fixed to the bearingengagement section by heat caulking welding, stress concentrated thereoncan be mitigated and mechanical strength can be insured by a conicallybeveled section provided in the edge section of a hole for a set pinsubjected to heat caulking when inserted therein and engaged therewith.

Also, the rotary shaft can precisely be positioned by engaging theengaging section 20a of the bearing 20 in the hole for engagement 25provided in the valve body (II) which is a shell body, and the rotaryshaft can be supported by engaging the bearing section 20b to the rotaryshaft from outside thereof. In this state, the resilient contactingpiece 20c always energizes the rotary shaft in the radial direction, sothat the rotary shaft can be prevented from becoming loose in thebearing hole and a function the bearing has by nature can accurately beoperated even if wearing of the liding section or change in a clearancethereof occurs.

Next description is made for a second embodiment of the suction controldevice for a multiple cylinder internal combustion engine according tothe present invention.

FIG. 31 shows a cross-sectional view of the suction control device takenalong the line B--B in FIG. 7, and the multiple butterfly valve foropening or closing the suction path 8 is provided in this area. As shownin this figure, in the multiple butterfly valve provided in the portionof valve body (II), a basic body of the valve 21 and a rotary shaft 21asupporting the basic body thereof are formed monolithically with a resinmaterial. And one end of the rotary shaft 21a described above issupported by the bearing 20 and the rotary shaft located between thebasic bodies of valves 21 is rotatably supported by the intermediatebearings 22.

Furthermore, an actuator 30 is connected to other end section of therotary shaft 21a to actuate the multiple butterfly valve describedabove. In the actuator 30, if a worm 32 is rotated by a driving sourcesuch as a motor (not shown herein), a worm wheel 31 which is a torquedelivery rotary member engaging therewith is rotated, then the rotaryshaft 21a fixed monolithically to the worm wheel 31 is rotated. Itshould be noted that the bearing 23 is provided in the section forconnection between the worm wheel 31 and the rotary shaft 21a, and theother end of multiple butterfly valve is rotatably supported thereby.Also, in the worm wheel 31, the internal side thereof is energizedoutwards by a coil spring 33 which is a resilient energizing member, andthe expanding piece 21b monolithically formed with the rotary shaft 21ais contacted with the contacting wall 24 formed in the internal wall ofthe valve body (II) via a washer 25 having lubricity for improvingsliding capability, thus effects as a thrust bearing being achieved.

With the thrust bearing structure described above, the expanding piece21b and the contacting wall 24 are always (via the washer 25) contactingto and engaging with each other so that a multiple butterfly valve canbe prevented from becoming loose in the axial direction because it isenergized by energizing power of the coil spring 33.

Also, in this case, as shown in FIG. 31, the coil spring 33 is providednear the contacting area between the expanding piece 21b and thecontacting piece 24, so that the energizing power can accurately andefficiently act to both of the contacting direction, and for this reasonthe multiple butterfly valve can precisely be positioned to the valvebody (II).

Furthermore, the contacting wall 24 formed in the valve body (II) andthe expanding piece 21b formed monolithically in the rotary shaft of themultiple butterfly valve described above are used as a reference pointrespectively for positioning thereof when each component aremanufactured and assembled respectively, so that locating each valve 21in the suction path 8 and sizing thereof can precisely be executed. Forthis reason, even if each component has been deformed caused by thermalexpansion, functions as a valve can accurately be executed withoutgenerating any interference between the valve and the internal wall ofthe suction path.

Next description is made for another embodiment of the thrust bearingstructure described above. FIG. 32 shows a cross-sectional view of thedevice in an area where the multiple butterfly valve is provided asshown in in FIG. 31. As shown in the figure, in the multiple butterflyvalve, one end of the rotary shaft 21a is engaged in and connected withthe worm wheel 31 which is a torque delivery rotary member, the end face31c thereof is contacted to the contacting piece 34a monolithicallyformed in the internal wall of cover 34 in the actuator 30. Also, thecoil spring 33 rotatably inserted into the end section bearing 20 iscontacting the rotary shaft in the other end of the rotary shaft 21a, sothat the rotary shaft 21a is energized to the side of the contactingpiece 34a.

Herein, description is made for connection between the worm wheel 31 andthe rotary shaft 21a. As shown in FIG. 33, a cylindrical section 31aprojecting from the peripheral surface thereof is provided in the wormwheel 31, and a hole for engagement 31b with a substantially rectangularand opening to the side of end section is formed inside thereof. On theother hand, formed at an end section of the rotary shaft 21a is anengaging shaft section 21c which are inserted and engaged in the holefor engagement 31b described above for rotating together with the rotaryshaft. With the connection by means of engagement between the engagingshaft section 21c and the hole for engagement 31b, torque is accuratelydelivered to each other without causing idling.

In the thrust bearing structure described above, the movement of therotary shaft can be controlled as well by positioning the rotary shaftto a specified position, thus the such a fault as rattling beingprevented.

Next description is made for a sequence of assembling a monolithic typeof multiple butterfly valve by using the intermediate bearing 22described above. At first, the rotary shaft positioned between valves islocated on the base section of the bearing 22k as shown in FIG. 16, thena pair of engaging pieces 22a are engaged in each other as describedabove to be locked with the hooks 22b thereof. Then the intermediatebearing 22 in the state described above is fixed to the bearing engagingsection formed in the valve body (II) by being inserted thereinto andengaged therein in the direction vertical to planes of FIG. 31 and FIG.32. At this time, the groove 22f and the arch-formed projecting section22g (refer to FIG. 18) formed in the intermediate bearing 22 are engagedin the long size projection section and arch-formed groove (not shown)formed in the bearing engaging section respectively, which enablesaccurate positioning of the intermediate bearing 22.

When the intermediate bearing has been positioned and fixed, in the nextprocess, one end of the rotary shaft 21a is inserted into the bearing 20in the axial direction, and the other thereof is connected to and fixedto the worm wheel 31 via the coil spring 33 in the embodiment shown inFIG. 31. On the other hand, in the embodiment shown in FIG. 32, atfirst, the engaging shaft 21c positioned at one end of the rotary shaftis engaged in the hole for engagement 31b of the worm wheel 31 fromoutside thereof in the axial direction of the rotary shaft 21a, and thecover 34 is mounted to the worm wheel from outside thereof so that thecontacting piece 34a is contacted and engaged in the end face 31c of theworm wheel 31. And the bearing 20 providing therein a coil spring 33 isengaged in the other end thereof to be in a state where the rotary shaft21a is energized to the side of the worm wheel. With steps describedabove, assembly of the multiple butterfly valve is complete. Herein, acoil spring 33 and the end section bearing 20 can monolithically beformed with a resin material. In this case, it is advantageous that acoil spring 33 is formed in a cantilever-form like that of the resilientengaging piece 22c described above.

It should be noted that, the expanding piece 21b formed monolithicallywith the rotary shaft 21a and projecting in the radial direction (whichcan not be employed in a structure in which a rotary shaft be insertedfrom the peripheral side of the valve body thereinto for engagement likein the conventional technology) can be employed only because the methodof assembling as described above is used.

As described above, with the suction control device for a multiplecylinder internal combustion engine, the expanding piece formedmonolithically in the rotary shaft 21a is contacted and engaged in thecontacting wall formed on the valve body which is a shell body, andfurthermore, for instance, the rotary shaft is directly energized by aresilient energizing member so that this engaged state can always bemaintained, and for this reason the rotary shaft does not become loose,and the multiple butterfly valve can accurately execute itsopening/closing operation in each of the suction paths.

Also, as each butterfly valve and a suction path are formed withreferring to a position wherein the expanding piece and the contactingwall are engaged with each other as a reference surface for positioning,positioning for each component as required in the conventionaltechnology is not necessary, which enables easier work for assembly anda higher precision in alignment.

Furthermore a torque delivery rotary member for delivering torque to therotary shaft is connected thereto by engagement, and the contactingpiece is contacted from outside of the end face to the rotary shaft withan energizing force added to the other end of the rotary shaft by aresilient energizing member, so that various advantages such asprevention of rattling of the rotary shaft and easiness in assemblythereof are provided. Namely the rotary shaft and the torque deliveryrotary member are not fixed to each other by a screw means or bywelding, but the two components described above are simply engaged inand connected to each other, so that after the rotary shaft has beenprovided in the valve body, the state where the rotary shaft isaccurately and precisely supported in the radial direction and thethrust direction can be maintained only by adding thereto inserting andengaging work from the axial direction.

As described above, by using resin as molding material, weight reductionof the device can be achieved and also accurate functions of themultiple butterfly valve is insured.

Next description is made for a third embodiment of the suction controldevice for a multiple cylinder internal combustion engine according tothe present invention.

FIG. 34 shows a plan view illustrating an appearance of the basic bodyof the suction device in a state where the throttle body 200 is fixed tothe basic body of suction device 100 by a connecting structure accordingto the present invention. As shown in the figure, the basic body of thesuction device 100 comprises a combination of components formed by resininjection molding and presenting the following three areas of I, II, andIII. Namely a portion of a branch (I) connected to the head intake portof engine, a portion of a valve body (II) presenting therein a multiplebutterfly valves each opening/closing the suction path, and a coveringportion (III) forming a surge tank and a roundabout suction path arediscretely molded each by injection molding, and then connected througha respective flange surface to form a monolithic body by vibrationwelding.

Also, the flange section 10a for mounting thereon the throttle body 200formed from an aluminium material or the like is monolithically formedwith the same resin material as that used for the basic body of suctiondevice 100 in the valve body portion (II) as well as for the coveringportion (III).

It should be noted that, in FIG. 34, the same reference numerals asthose in FIG. 4 are used to indicate the portions previously described.

Next detailed description is made for the flange section 10a molded froma resin material. FIG. 35 shows a side view illustrating the basic bodyof suction device 100 from the point of the arrow R in FIG. 34 (showinga state where the throttle body 200 has not been located therein), and,as shown in the figure, the flange section 10a has a substantiallyrectangular form and an opening section 10b communicating the internalsection of the surge tank to outside air is formed in the centralsection thereof.

Also, U-shaped notched engaging grooves 10c opening to outside in thediagonal direction of the flange face each are provided at four cornersof the flange section 10a describe above. Then a cylindrical screwsection 11a of the nut 11 with flange which is a portion of theconnecting means described later is engaged in parallel with the flangeface at the notched engaging groove 10c.

Next detailed description is made for an engaged relation between thenotched engaging groove 10c and the nut 11. FIG. 36 and FIG. 37respectively show views for explanation of the engagement relationdescribed above, and FIG. 36 is a perspective view illustrating anappearance of a flange section 10 area of the suction system surge tank,while FIG. 37 is a partially enlarged view illustrating a state wherethe nut 11 is engaged in the notched engaging groove 10c. As shown inthese two figures, a pair of projections 10d each opposed to theinternal walls of the grooves are formed at the U-shaped notchedengaging groove 10c provided at four corners of the flange sections 10a,and this portion is narrower in width as compared to other groove width.On the other hand, a nut 11 which is a portion of the connectingcomprises a cylindrical screw section 11a in which a female screw groove11c is formed in its internal wall and a rectangular flange section 11bhaving a width in the radial direction provided in the end section ofthe axial direction of the cylindrical screw section. And when a nutwith flange 11 is to be inserted into and engaged in the notchedengaging groove 10c, the cylindrical screw section of a nut with flange11 is inserted from the side of opening of the notched engaging groovethereinto, and contacted to a pair of projections 10d, and herein,pushed thereinto by adding further a force to the cylindrical screwsection, so that the cylindrical screw section 11a reaches the bottomsection 10e of the notched engaging groove 10c, then the screw sectionis fixed so that it is held by the internal wall of the notched engaginggroove 10c and the pair of projections 10d. At the same time, the pairof projections 10d are deformed within a range of their elasticity whenthe cylindrical screw section 11a is pushed into the groove, whichenables insertion thereof, then the resilience of the projectionsrecovered after their engagement is complete, namely a perimeter of thecylindrical screw section kept held and fixed therebetween by theirspring action, so that a nut is prevented from dropping until when thethrottle body 200 has completely been tightened and fixed.

The method of engaging a nut 11 in a U-shaped engaging groove 10c havingan opening in one end in a direction parallel to a flange face is one ofthe most preferable methods of mounting especially in a case where noextra space is behind a flange face of the flange section 10a in thevertical direction. Because a circle hole can be employed if a movingstroke for inserting a cylindrical screw section can be ensured in thedirection vertical to the flange face.

Next description is made for a connecting method when a throttle body200 is assembled to the basic body of suction device 100. FIG. 38 showsa cross-sectional view illustrating the basic body of suction devicetaken along the line J--J in FIG. 34, and as shown in the figure, thenut with flange 11 is engaged in the flange section 10a of the basicbody of suction device in a state where a flat washer 13 and a pair ofcounter-sunk springs 12 are provided between the flange section 11b ofthe nut with flange 11 described above and the end face of the flangesection 10a. And the flange section 200a of the throttle body 200 iscontacted to the flange section 10a of the basic body of suction devicevia a seal member 400 so that two of the flange faces can firmly bestuck to each other, and furthermore the volt 300 incorporating thereina flat washer 500 is screwed to the screw groove 11c of the nut withflange 11 through the through-hole 200h.

With the connecting structure described above, the flange section 10aformed with a resin material is always energized to the flange section200a of the throttle body to be stuck by a counter-sunk spring 12.

For this reason, even if the resin flange section 10a generatespermanent distortion (settling) due to heat creep such as compression ordeformation, the reduction in contacting strength with which thethrottle body is stuck to the basic body thereof can be prevented by aspring power of the counter sunk spring, so that the connecting state ofthe two can accurately be secured from external vibration. Especially,if a deformation rate of the resin flange section 10a is large, as shownin FIG. 38, it is preferable to provide a counter-sunk spring 12 in theside of flange section 10a because the spring power is directly effectedthereover.

On the other hand, if a deformation rate of the resin flange section 10ais not so large, as shown in FIG. 39, it is allowable to employ a methodof locating a plate (counter-sunk) spring 12 in the side of the flangesection 200a of the throttle body by using the conventional type of volt300 and nut 700.

Furthermore, in the structure where a nut with flange 11 is used asshown in FIG. 38, by forming a whirl-stop wall 10m or a drop-preventingwall 10n on a portion of the external wall of the basic body of thesuction device 100, dropping of a nut can be prevented even if anengaged state between a nut with flange 11 and a notched engaging groove10c is not tight enough. Therefore, a technique may be employed in whichonly the nut with flange 11 with a flat spring 12 and flat washer 13previously incorporated therewith is assembled to a flange section ofthe flange surface 10a of the basic body of the suction device, and thethrottle is assembled thereto in a different process, which insureseasiness in a work for manufacturing and assembly and insures a largerfreedom in a designing process.

As described above, with the structure for connection according to thepresent invention, a nut with flange comprising a cylindrical screwsection having a female screw groove on the internal wall thereof and arectangular flange section having a width in the radial direction at anend section in the axial direction of the cylindrical screw sectiondescribed above is employed, and furthermore, a U-shaped notchedengaging groove with one side opening to outside in the direction offlange face is formed in the flange section formed from a resinmaterial, and a projection pressing the cylindrical screw section to thebottom section of the engaging groove in the state where the cylindricalscrew section of the nut with flange is engaged in the engaging grooveis provided in the internal wall of the engaging groove, so that it iseasy to assemble the nut with flange to the flange section and the nutcan be prevented from dropping, and for this reason, a nut is notrequired to be used held when tightening, and the tightening work caneasily be carried out.

Also, by providing a resilient member energizing the flange section to aflange section in the other side in the side of flange section formedwith a resin material, the flange section is connected with bolts andnuts. Therefore, even if the resin flange section generates plasticdeformation due to heat creep or the like, reduction of the axialstrength can be suppressed, so that contacted state of the two flangesection can be maintained and also firm connection between the twocomponents can strongly be maintained.

INDUSTRIAL AVAILABILITY

As described above, the suction control device for a multiple cylinderinternal combustion engine according to the present invention canaccurately executes the original functions thereof without fail and alsoenables weight reduction, so that it can advantageously and effectivelybe used in a combustion engine mounted on a vehicle or the like becauseof the fuel cost reduction realized by weight reduction.

What is claimed is:
 1. A suction control device for a multiple cylinderinternal combustion engine comprising:a shell body being made from aresin material, and having suction paths each communicated to eachcylinder in a multi-cylinder internal combustion engine; a rotary shaftpenetrating and born by said shell body; butterfly valves each supportedby said rotary shaft and provided in each of said suction paths so thatsaid butterfly valves can freely open or close said suction pathsrespectively; and a bearing fixed onto said shell body and supportingsaid rotary shaft so that said rotary shaft can freely rotate, saidbutterfly valves and said rotary shaft being made from a monolithicallymolded resin material, said rotary shaft having a curved surface sectionin a border area between each pair of neighboring ones of said butterflyvalves, each of said butterfly valves including a padding section havinga streamlined form in the intake air flowing direction in a border areabetween said rotary shaft and each of said butterfly valves, and saidbearing comprising: a pair of engaging pieces being engageable with eachother so as to radially bear said rotary shaft therebetween when theyare engaged with each other, and a resilient contacting piecemonolithically formed in a portion facing said rotary shaft of each ofsaid engaging piece for radially urging said rotary shaft.
 2. Thesuction control device for a multiple cylinder internal combustionengine according to claim 1, wherein said pair of engaging pieces areconnected to each other in one of their respective end sections.
 3. Thesuction control device for a multiple cylinder internal combustionengine according to claim 1, wherein each of said pair of engagingpieces is discretely formed as a separate body.
 4. The suction controldevice for a multiple cylinder internal combustion engine according toclaim 1, wherein said bearing further includes a base section whichsupports a portion of the periphery of said rotary shaft, and whereineach of said pair of engaging pieces is monolithically formed with saidbase section while being movable relative to each other.
 5. The suctioncontrol device for a multiple cylinder internal combustion engineaccording to claim 1, wherein said shell body has a fixing pin forfixing said pair of engaging pieces to said shell body by means of heatcaulking welding, and wherein each of said pair of engaging pieces has ahole for said fixing pin to be inserted therein and engaged therewith inan end section away from a section for supporting said rotary shaft insaid engaging piece and also has a conical beveled section in an edgesection of said hole for insertion and engagement in the side forheat-caulking welding.